1. Field of the Invention
This invention is in the field of hand-held grinders or sanders used to prepare workpiece surfaces for painting or receiving other finishes or no further finish.
2. Description of Prior Art
A wide variety of equipment has been and currently is in use to give wood, concrete, or metal surfaces a uniform surface finish pleasing to the eye. Sanding or grinding surfaces flat is commonly required, either as a final finish or in preparation for painting, coating, or plating. My invention is primarily directed to improving hand-held machines using rotating circular discs, made of abrasive or coated on the lower (contact) surface with abrasive and brought by hand into contact with the workpiece surface, which in most cases is flat. The thrust of my improvements has to do with handling the dust and grit particles thrown off the perimeter of the rotating circular disc.
The state-of-the-art is that machine and device manufacturers have increasingly taken steps to capture airborne debris before an operator or bystander inhales it. Suction blowers incorporated into the machine, either on the electric drive motor shaft or on the shaft which carries the abrasive disc, are standard components. Various types of bags in which to collect the debris have been used, the usual arrangement being a cloth or paper bag on the side of the machine which has the problem that due to gravity it droops down onto the working surface as it fills. Suction ports of quite a few different designs are located in the vicinity of the disc periphery. Many of these have dead areas; only collecting part of the debris since they do not surround the disc fully and completely. Most allow the debris-laden air to leave the disc radially and then try to bend the airstream through a 90 degree angle to an upward direction toward the suction blower inlet. Since the debris particles are heavier than air, not all of them "make" the turn.
There is also an operational problem with current art in that obstructions such as inside corners on the workpiece, partially withdrawn nails and the like can contact the spinning disc causing sudden, unpredictable and unexpected forces on the machine and hence on the operator's hand. This element of danger, as well as the health/environmentally undesirable consequences of debris in the free air, are virtually eliminated by my invention.